Drilling device

ABSTRACT

A drilling device has a frame (1) with a feed device (2) for carrying a drilling device (3) movable to-and-fro for rotating a drill string (4). The drilling device includes a sensor (6) for sensing an end (7) of a drill string element (8) in the drill string (4), and a register for the position of the end (7) along the feed device (2) and for the displacement of the drilling device (3) along the feed device (2).

BACKGROUND OF THE INVENTION

The present invention relates to a drilling device of the type used fordrilling in rock or earth layers or similar. More specifically theinvention relates to a drilling device which is suitable for drillingwith long drill strings comprising a large number of drill stringelements which may have somewhat different lengths.

In prior art drilling devices, e.g. for exploration drilling, of thekind which the present invention aims at improving it is important forachieving good efficiency in the handling of the drill string to havetwo operators, one who handles the drilling machine and one who handlesthe drill string elements. In exploration drilling this handling is verytime-consuming since one takes up drill samples every third meter or soand the drill string comprises several hundred drill string elements.

SUMMARY OF THE INVENTION

The present invention which is defined in the subsequent claims aims atachieving a drilling device where drilling and handling of the drillstring efficiently can be handled by one operator independent ofvariations in tube length drill string weight drilling direction andstarting position. In particular, the invention makes it possible toautomatically make and break joints between drill string elements havingeven surfaces and substantially constant diameters.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is described below with reference to theaccompanying drawing in which

FIG. 1 shows a side view of a drilling device according to theinvention.

FIG. 2 shows a part of the drilling device in FIG. 1 on a larger scale.

DESCRIPTION OF THE BEST MODE FOR CARRYING OUT THE INVENTION

The drilling device shown in the drawing comprises a frame 1 on which afeed device 2 is arranged. The frame can be in the form of a sleigh asshown in FIG. 1 or a vehicle or some other arrangement carrying the feeddevice in a stable manner. The feed device 2 comprises in the shownexample two sprockets 11, 12 and a chain 13 which passes over thesprockets and is connected with a drilling device 3. The teed device canbe made in in arbitrary wax which allows displacement of the drillingunit 3 to-and-fro along the feed device. The drilling device 3 comprisesa rotation motor 14 which via a gear box 15 rotates a chuck 16. Thedrilling device has a through passage for a drill string 4.

The chuck 16 comprises gripping means which can be brought into contactthe drill string for rotation of the drill string. The chuck is arrangedfor gripping or releasing the drill string 4 under fluid pressurecontrol. A holder 5 for the drill string 4 is arranged at the lower andof the feed device 2. Cooperation between the chuck 16, the holder 5,the feed device 2 and the drilling device 3 can be as described in U.S.Pat. No. 3,613,804. The holder 5 comprises gripping means for grippingor releasing the drill string under fluid pressure control. Oneimportant aspect of the present invention is the possibility ofautomatically making or breaking the joints between two drill stringelements 8. This is done through gripping the drill string 4 with boththe chuck 16 and the holder 5 and rotating the chuck in either directiondepending on what is desired. In this respect it is important that thedrilling device is movable along the feed device to make it possible toapply torque to the drill string. With the present invention this can beobtained with drill string elements having an even surface andsubstantially constant outer diameter.

The drilling device 3 is provided with means 6 for the sensing of an end7 of a drill string element 8 being a part of the drill string 4. In theshown example one uses an infra-red light source and a sensor forinfra-red light. One can also use other means, e.g. mechanical sensing.The feed device 2 furthermore comprises a meter 22 for measuring theposition of the drilling device 3 along the feed device. The drillingdevice 3 is provided with speed counter 23 for indication of therotational speed of the drilling device and thus also indication ifrotation exists or not. Signals from the different transmitters are fedvia cables 21 to a means 9 for registering the position of the end 7relative to the drilling device 3. This is done when the end 7 passesthe infra-red light at 6. The means 9 for registering is also used forregistering the displacement of the drilling device 3 along the feeddevice and for registering the rotation of the feed device. In the shownexample the unit 9 comprises a computer for controlling the differentfunctions during drilling, when adding drill string elements and whentaking away drill string elements. This makes a high degree ofautomation of the drill string handling possible. Through sensing theend of a drill string element one can achieve automation of the handlingof the drill string elements in the drilling device. This is achievedthrough adjusting the registering means 9 for each drill string elementfor variations in the position of the drill string element so that oneall the time knows where the joint between two drill string elements issituated even if the drill string has a large number. e.g. 500 drillstring elements. The difficulty in achieving an automatic withdrawal orinsertion of a large number of connected drill string elements has beenthe addition of errors in the position of the end of the drill stringelements. These errors depend on smaller variations in the lengths ofthe drill string elements or on that the drill string glides somewhat inthe holder 5 or the chuck 16.

The drilling device shown in the drawing works in the following way whenthe drill string 4 is inserted in a bore hole 31. In the startingposition the holder 5 is closed so that the part of the drill string 4in the bore hole 31 is held by the holder. Furthermore a drill stringelement 8 has been screwed on by hand about one turn. The chuck 16 isopen. In this position the automatic insertion is started, e.g. by meansof a pedal. The drilling device 3 is fed upward along the feed device 2to a predetermined position. The chuck 16 is closed. The chuck 16 isrotated so that the joint situated between the holder 5 and the chuck 16is screwed together. The check that so has occurred is that the chuckhas iotated a predetermined number of turns and that the rotationalspeed has decreased to zero. The holder 5 is opened and the drillingdevice 3 is fed downward so that the drill string 4 is fed into the borehole 31. The holder 5 is closed and the chuck 16 opened. Then thedrilling device 3 is fed upward until the upper end 7 of the drillstring element 8 is sensed by the sensing means 6. Maybe one must gripseveral times with intermediate feeding in of the drill string if thedrill string elements are longer than the feed length of the feed device2. Then the drilling. Device 3 is fed downward a predetermined distancein order to have the end 7 of the drill string in a suitable positionrelative to the drilling device. The chuck 16 is closed, the holder 5opened and the drilling device 3 is fed downward so that the drillstring is fed into the bore hole 31. Then the holder 5 is closed and thechuck 16 opened. After that the operator adds a drill string element tothe drill string and the above described cycle is repeated until theentire drill string has been fed into the drill hole. The computer inthe registering means 9 keeps a track of how many drill string elementshave been fed into the bore hole and where the joints are relative tothe drilling device.

When the drill string has reached the hole bottom drilling starts. Theoperator sets the desired drilling parameters. The automatics in theregistering, device 9 then controls the drilling process so that the setvalues are maintained. Through this automates the operator is relieved.Furthermore a substantially improved control precision is obtained thanwhat is possible manually. Through this the wear of the drill bit isdecreased substantially.

When drilling is interrupted, e.g. because the core barrel is full orbecause the drill bit need being replaced, the drill string should befed out of the hole. When withdrawing the cycle is started, for instancewith the above mentioned pedal. The process is the opposite to the oneof insertion. The automatics keeps track of where the end of the drillstring is positioned and the operator takes out the drill stringelements instead of adding them.

We claim:
 1. Drilling device comprising a frame (1), a feed device (2)on the frame for a drilling device (3) being movable to-and-fro alongthe feed device and comprising a chuck (16) for gripping or releasing adrill string (4) under fluid pressure control for rotation of the drillstring (4), a holder (5) for the drill string (4) arranged on the feeddevice (2) for gripping or releasing the drill string (4) under fluidpressure control, characterized by means (6) for sensing an end (7) of adrill string element (8) forming part of the drill string (4), saiddrill string elements (8) having a substantially constant diameter alongtheir length, and means (9) for registering the position of said end (7)along the feed device (2) relative to said drilling device (3), forpositioning the end 7) on the drill string element (8) to apredetermined position alone the feed device (2).
 2. Drilling deviceaccording to claim 1, characterized in that said means for sensing saidend (7) comprises a light source (6), and a sensor for this lightsource.
 3. Drilling device according to claim 2, characterized in thatsaid light source (6) is for infra-red light.